1. Field of the Invention
Many years ago Weber Marking Systems, Inc., the assignee of the present application, and its predecessors pioneered in the development of utilizing a removably attached stencil over the address portion of a multi-leaved invoice form whereby one typing of the customer's name and address completed the addressing of the invoice and the making of a stencil used to address the packages comprising the shipment. This one typing eliminated the error of having goods shipped to one address and sending the invoice to a different address. Weber Marking Systems, Inc. has experimented with many types of adhesives in their removable attachment of stencils to plural leaved invoice forms. Both the adhesives and the stencils contained oils and with the passage of time these oils tended to "bleed" and contributed to a staining of the invoice forms. Weber Marking Systems, Inc. discovered that by using a pressure sensitive adhesive tape to hold the stencil to the paper form there was a minimum of oil bleed onto the paper form. A novel tabbing machine was developed and this is disclosed in Weber Marking Systems, Inc. U.S. Pat. No. 3,052,284.
However, there were and are drawbacks to the tabber utilizing a separate tape to attach the stencil to the forms to be addressed. Shelf life of such stencil tabbed forms is relatively short and hence the forms with stencils tabbed thereto cannot be made up in advance of their intended use. Also, stencils having a pressure sensitive adhesive tape at one end thereof makes such a stencil roll special. And still further such special stencil rolls are bulky at the one end and not the other making it difficult to make uniformly wound rolls.
The present invention aids in overcoming some of the inadequacies of the existing tabbing system with tape adhered stencils. The adhesive utilized is preferably a non-oily wax which securely holds a stencil without smearing or causing oil bleedout to the form of which the stencil is attached. The stencils may be of standard construction without the use of bulky tape. And, effective shelf life of these wax held stencils is considerably longer than those heretofore used.
The present applicator employs an adhesive storage chamber, an applicator chamber and an intermediate metering chamber with separate valve means interposed between the storage chamber and the intermediate chamber and between the intermediate chamber and the applicator chamber. The separate valve means are arranged to alternately open and close in such a manner that the valve between the storage chamber and the intermediate chamber is open when the other valve is closed. And, conversely when the first valve closes the other valve opens to permit discharge of adhesive from the intermediate chamber to the applicator chamber. The valves are operated by the applicator being pressed down onto the paper form to receive the deposition of wax adhesive. This downward pressing causes a relative movement of portions of the applicator chamber to effect valve actuation and to pump a charge of the adhesive in a desired pattern onto the paper form. The applicator chamber is provided with an opening along the surface engaging the paper form to receive the adhesive. A flexible plastic material is provided in the applicator chamber to control the passage of adhesive through the applicator opening. The plastic material has differential densities of porosity and further is provided with an impermeable coating over selected areas to effect the desired controlling of the liquid flow therethrough.
2. Description of the Prior Art
A preliminary patent search was made on the subject liquid application and the following prior patents were found:
______________________________________ Talarico 3,344,767 Lockwood 3,348,520 Abrams et al 3,614,940 Maniaci 3,642,556 Schweitzer 3,768,439 Baker et al 3,811,405 Carlyle 3,818,924 ______________________________________
Most of the above listed prior patents show and describe mechanisms for dispensing adhesives or other liquids in various patterns. Some of these patented devices employ valved trap chambers to dispense uniform amounts of liquid on each ejection. Still further some of these prior patented devices also employ heating chambers to melt the liquids before they are dispensed.
The patent to Abrams et al employs a porous nib through which a marking fluid is forced. This is the only reference which uses a porous plastic material to control the deposit of a liquid. The Abrams et al nib is not described as having anything but a single porous density. There is no teaching of differential porous densities in the Abrams et al nib, nor is there any teaching of the use of a liquid impermeable coating to control the points of discharge through the Abrams et al nib.
All of these prior patents fail to disclose the principles of applicant's invention as disclosed herein.